This guest opinion is by Susan Allan, M.D., J.D., M.P.H, Administrator of the Oregon Department of Human Services Public Health Division.

Length: 423 words (including writer ident.)

By Susan Allan, M.D.

Whether it's the start of flu season, food safety during family celebrations or close contact with family and friends who may be carrying germs, public health experts in the Oregon Department of Human Services say one simple action can protect your health: handwashing.

Hands carry germs. It's common knowledge, right? After all, for years, mothers everywhere have drummed the message: wash your hands! But here are some important handwashing facts you may not know:

Colds, flu, intestinal illness or staph infection -- whatever the bug may be, handwashing is the single most important thing you can do to keep from getting sick and to avoid spreading illness to others.

Adequate handwashing requires soap and clean, running water. Warm water is preferable. Lather up and scrub for 20 seconds, or the time it takes to sing the "Happy Birthday" song two times through.

Why use soap? It mixes with skin oil and loosens grease and dirt that may hold germs.

Plain soap is a better choice than antibacterial soaps.

Soap and water are preferable for cleaning hands, but if none is available use an alcohol-based gel as a substitute.

Wash your hands often. The average person touches eyes, nose and mouth -- which are the easiest ways germs get inside the body -- at least 200 times a day.

The most important times to wash hands are before preparing or eating food, after going to the bathroom or diapering a child, before and after caring for someone who is sick or bleeding, after blowing your nose, coughing or sneezing and after handling an animal, animal waste or garbage.

Nationally, inadequate handwashing may cause up to 40 percent of diarrheal illness and 20.000 hospital-acquired deaths, and costs millions of dollars in sick leave each year, according to the federal Centers for Disease Control and Prevention.

No matter how old you are, handwashing reminders are important: A 2005 national study found that 91 percent of adults said they always washed their hands after using public restrooms, yet just 83 percent were observed doing so. Seventy-seven percent said they always washed their hands before handling or eating food. Just 42 percent said they washed their hands after petting a dog or cat, and only 32 percent did so after coughing or sneezing.

The complete study, conducted by the American Society for Microbiology and the Soap and Detergent Association, is on the Web at www​.washup.org